Field-coil and method of making same.



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D. L E I ...I H C ml. I L D. W L o0 4| 4 nu 7 nu N FILD COIL AND METHOD 0F MAKING SAME.

APPLICATION FILED 00T.10, 1902.

N0 MODEL.

.C .m .f mm .Lum HL e. vm .me W a W UNITED STATES Patented July 5, 1904.

PATENT OEEicE.

VALTER D. LITCHFIELD, OF SCHENFCTADY, NEV YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEV YORK.

FIELD-COIL AND METHOD OF MAKING SAVIE.

SPECIFICATION forming part of Letters Patent No. 764,481, dated July 5, 1904. Application filed October 10, 1902. Serial No. 126,678. (No model.)

To all whom it may concern:

Be it known that I, WALTER D. LrroI-IFIELD, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Field-Coils and Methods of Making the Same, of which the following is a specilication.

This invention relates to field-coils for dynamo-electric generators, and its object is to reduce the weight and size of such coils without reducing the weight of copper employed or impairing the insulation.

A further object is to improve the heat-radiating capacity of the coil so that it will run cooler.

ln order that the several steps of my method of making field-coils may be better understood, reference may be had to the accompanying drawings, in whichH Figure l is a perspective view of an insulated copper ribbon wound into a pancake coilsection. Fig. 2 shows said coil-section with the edges of the ribbon painted with insulation and aterminal connection secured to one end of the ribbon. Fig. 3 is an elevation, partly in section, of tour coil-sections placed side by side and electrically connected. Fig. 4 is a similar view showing the coil wound with insulating-tape. Fig. 5 shows this coil after treatment with japan and partial unwrapping. Fig. 6 shows the coil partially rewrapped. Fig. 7 is a perspective view of the finished coil. A

The pancake coil-section 1 shown in Fig. 1 is made by winding on a former a copper ribbon which has been insulated by an oil enamel, such as that patented to Clark and Rupley, No. 687,518. The edges of the ribbon are then painted with this enamel to till in all interstices and cavities and produce a smooth flat surface 2, as shown in Fig. 2. The section is then baked at the proper temperature, after which a plurality of such sections are assembled side by side, as shown in Fig. 3, adjacent sections being reversed in relation to the direction of their windings. The adjacent inner and outer ends are then connected, as by plates 3, so as to form a continuous winding in the same direction around the pole-piece oi' the generator. For example, when four sections are assembled the current will start at, say, the terminal 4 on the outside oi' the righthand section and travel clockwise to the center, then across a connecting-plate 3 to the center ot' the second section and clockwise to the outside of the same, then across a connecting-plate 5 to the outer end of the third section and clockwise to its center, then across the second connectingplate 3 tothe centeroil the fourth section and clockwise to the outside otl the same to the terminal 6. A sheet 7 of asbestos or other suitable insulation is placed between each two adjacent sections to serve not only as additional insulation, but as a cushion to prevent the sections from rubbing against each other. The whole is then bound together with two wrappings 8 of cotton tape and treated with hot Japan varnish or other liquid insulating compound, either by the vacuum process or by simple dipping. This iills all the minute air-spaces throughout the coil with the insulating liquid, which not only binds all parts together, but makes the coil impervious to moisture and helps to insulate one section from the other. Moreover, by filling the air-spaces the capacity ot' the coil to radiate heat is increased.

After baking for a suitable time the outercotton wrapping is removed, taking with it all air-bubbles and uneven bunches 9 of the japan or other compound. (See Fig. 5.) An insulating-wrapping 10 is then put on, and this is covered with a protective webbing or cloth 11 to serve as a mechanical protection to the insulation lO, Fig. 6. The coil is then dipped in japan or other insulatingcompound to till this outside covering and is linally baked. The finished coil is shown in Fig. 7. This mode et' construction makes a very compact solid coil in which a maximum of copper occupies a minimum of space, so that in a machine of given dimensions more ampereturns are possible, or, conversely, for a given number of turns less space is required, thereby making the entire machine smaller and lighter.

As a moditication of the above-described method two coil-sections may be wound continuously, the winding-form being reversed after the first section is wound and the end of the ribbon for the second section being fastened to the inner end of the first. The second section is then wound up alongside the first, but in the opposite direction, a sheet of suitable insulation having been placed on the winding-form beside the first section, so that it will lie between the two sections. When they are removed from the winding-form, the two sections are bound together with cotton tape, and the subsequent steps of building the complete co'il are as previously described.

What I claim as new, and desire to secure by Letters Patent of the United States, is# 1. The method of making a coil for a dynamo-electric machine, which consists in winding a plurality of sections of enameled conductor, alternate sections being wound in opposite directions, coating the sides of said sections with enamel, assembling said sections vside by side with insulation between them,

connecting the adjacent inner and outer ends of said sections, alternately, wrapping the coil in two layers of tape, dipping it in an insulating compound and baking, removing the outer wrapping, putting on a wrapping of insulation and a protective cover of fabric, dipping in insulating compound, and baking.

2. The method of making a coil for a dynamo-electric machine, which consists in Winding a plurality of coil-sections of insulated conductor, assembling said sections side by side, the inner and outer ends of said sections being alternately connected, covering the coil with two layers of insulating fabric, applying a liquid insulation, removing one layer of fabric, putting on a fresh covering of insulating fabric, and applying' liquid insulation.

3. A coil for a dynamo-electric machine, composed of a plurality of wound sections of copper conductor coated with a flexible encomposed of a plurality of wound sections of A copper conductor coated with a iexible enamel, a wrapping of tape, insulating compound filling the interstices, and an outer wrapping.

5. The method of making a coil for a dynamo-electric machine, which consists in winding a plurality of coil-sections of enameled conductor, coating the edges of said conductor with enamel and baking the sections, assembling said sections side by side, connecting the inner and outer ends of the several sectionsalternately, and covering the coil with a fabric.

6. The method of making' a coil for a dynamo-electric machine, which consists in winding a plurality of coil-sections of insulated conductor, assembling said sections side by side, connecting' the inner and outer ends of the several sections alternately, wrapping the coil with fabric, applying an insulating compound to the coil, and wrapping it in another covering of fabric. v

7 The method of making a coil for a dynamo-electric machine, which consists in winding a plurality of coil-sections of insulated conductor, assembling the sections side by side and electrically connecting them, wrapping the coil with tape, applying an insulating compound thereto and baking, wrapping the coil with insulating fabric, and covering it with a protective webbing.

In witness whereof I have hereunto set my hand this 8th day of October, 1902.

WALTER D. LlTCHFIELD.

Witnesses:

BENJAMIN B. HULL, HELEN ORFORD. 

